Year	current US$
2000	21.24717701
2001	19.43978989
2002	19.45404413
2003	20.71297342
2004	21.94461363
2005	25.06786351
2006	18.30090611
2007	18.60995164
2008	22.0104808
2009	23.91043639
2010	24.55595115
2011	25.0503666
2012	27.18208515
2013	26.15998208
2014	27.57942283
2015	26.19371983
2016	24.9356905
2017	29.3573559
2018	27.87337244
2019	25.07060941
2020	32.1647111
2021	32.95560846